Difference between revisions of "Regenerative Agriculture"

Latest revision as of 18:02, 30 May 2020

(this is a preliminary article, currently serving as a link dump)

This refers specifically to the animal-based and specifically grazing-based Regenerative Agriculture as advocated by Allan Savory of the Savory Institute and similar proponents/organizations like Tony Lovell, Bruce Ward, and other "Holistic Management" organizations.

The most important (and not-vegan) reference to summarize the science is the FCRN report "Grazed and Confused" found here: https://www.fcrn.org.uk/projects/grazed-and-confused

George Monbiot of the Guardian has also penned some of the earliest articles discrediting the bad science behind regenerative animal agriculture: https://www.theguardian.com/environment/georgemonbiot/2014/aug/04/eat-more-meat-and-save-the-world-the-latest-implausible-farming-miracle (there are responses to this article, and responses to those responses to be found)

"Reformed food reformer" Adam Merberg provides insights here in a brief article: http://www.inexactchange.org/blog/2013/03/11/cows-against-climate-change/

Regarding carbon sequestration: "Disturbance by ploughing and/or grazing significantly reduced SOC" (Soil Organic Carbon) https://www.sciencedirect.com/science/article/abs/pii/S0167880913000285

"Results show that areas used by domestic livestock have 20% less plant cover and 100% less soil organic carbon and nitrogen compared to relict sites browsed by native ungulates. In actively grazed sites, domestic livestock grazing also appears to lead to clustered, rather than random, spatial distribution of soil resources. Magnetic susceptibility, a proxy for soil stability in this region, suggests that grazing increases soil erosion leading to an increase in the area of nutrient-depleted bare ground. Overall, these results, combined with previous studies in the region, suggest that livestock grazing affects both plant cover and soil fertility with potential long-term implications for the sustainability of grazing operations in this semi-arid landscape."

https://www.sciencedirect.com/science/article/abs/pii/S0140196307002662

Once equilibrium is reached, grazing is *worse* than feedlots. Beef is always worse than other food production processes.

"We used ISO-compliant life cycle assessment (LCA) to compare the cumulative energy use, ecological footprint, greenhouse gas emissions and eutrophying emissions associated with models of three beef production strategies as currently practiced in the Upper Midwestern United States. Specifically we examined systems where calves were either: weaned directly to feedlots; weaned to out-of-state wheat pastures (backgrounded) then finished in feedlots; or finished wholly on managed pasture and hay. Impacts per live-weight kg of beef produced were highest for pasture-finished beef for all impact categories and lowest for feedlot-finished beef, assuming equilibrium conditions in soil organic carbon fluxes across systems. A sensitivity analysis indicated the possibility of substantial reductions in net greenhouse gas emissions for pasture systems under conditions of positive soil organic carbon sequestration potential. Forage utilization rates were also found to have a modest influence on impact levels in pasture-based beef production. Three measures of resource use efficiency were applied and indicated that beef production, whether feedlot or pasture-based, generates lower edible resource returns on material/energy investment relative to other food production strategies."

https://www.sciencedirect.com/science/article/abs/pii/S0308521X10000399

"This commentary summarizes the evidence supporting holistic management (HM) and intensive rotational grazing (IRG) to demonstrate the extent to which Sherren and coauthors (2012) have overstated their policy endorsement of HM for rangeland application. Five major points are presented – distinction between HM and IRG, insufficient evaluation of the contradictory evidence, limitations of the experimental approach, additional costs associated with IRG, and heterogeneous capabilities and goals of graziers’ to manage intensive strategies – to justify why this policy endorsement is ill-advised. The vast majority of experimental evidence does not support claims of enhanced ecological benefits in IRG compared to other grazing strategies, including the capacity to increase storage of soil organic carbon."

https://www.sciencedirect.com/science/article/abs/pii/S0308521X13001480

Other links: https://www.hindawi.com/journals/ijbd/2014/163431/

FCRN also has a response document, but the link is broken: https://www.fcrn.org.uk/projects/grazed-and-confused FCRN Response to the Sustainable Food Trust commentary on Grazed and Confused. (Note to editors, we should fetch this from archives or elsewhere, and possibly inform the webmaster of FCRN to fix the problem if it doesn't resolve)

This article explains the implausible (extraordinary) claims of many regenerative agriculture proponents and why they require better evidence (from somebody sympathetic to the principles of regenerative agriculture and grazing positive) http://csanr.wsu.edu/regen-ag-solid-principles-extraordinary-claims/

Increasing soil organic matter by a few percentage points is normally thought of as a long, difficult process, unless you use a lot of imported manure or compost. Here, however, Brown claims to have increased SOM by over 9 percentage points. How? According to the slide, by cover crops, multi-species cover crops, and livestock integration. Let’s do the numbers according to what current soil science tells us this would require.

First, some assumptions. My calculations are for the top 6” of soil for all 20 years. This ignores the increased topsoil depth shown on the slide and is therefore conservative. I am assuming that what Brown is showing is real organic matter, and not just undecomposed plant roots or shoots. Soil organic matter is not all organic material in the soil, it is the result of a complex biological process, with the resulting organic matter having very different properties from plant roots or shoots.

In the process from plant (or microbe) biomass to SOM, losses of mass (CO2 released to the atmosphere) range from 80-90% PDF. I assumed a loss of 85%, equivalent to a plant/microbe mass to SOM mass conversion rate of 15%. I took the nutrient contents of SOM from this NRCS publication PDF.

For ease of calculations, I assumed a constant rate of SOM increase. In reality, it is generally easier to increase SOM when levels are lower and more difficult as they get higher. Now we are ready for the calculations.

First, the amount of plant biomass required to obtain Brown’s increase in SOM. Given the 15% conversion rate, he would have had to add 31 tons (dry), per acre, of plant or other biomass to the soil, every year, for 20 years (see figure 1). If 31 tons does not mean much to you, it is more than the entire aboveground biomass of a fully fertilized, irrigated corn crop. It is more than a full season, four cuttings, of irrigated alfalfa hay production. It’s a lot of biomass. And this amount of biomass was added to the soil –what was harvested as a crop or as meat through livestock grazing is in addition to this 31 tons per acre per year.

Building soil organic matter requires more than biomass; nutrients are also needed, either in the added biomass or from the soil. SOM averages 5% nitrogen and 0.5% phosphorus. So then, Brown’s SOM increase requires 470 lb. of nitrogen and 47 lb. of phosphorus per acre, each year, for 20 years. This is more nitrogen than is applied to a high yielding irrigated potato crop, and as much as is harvested in a 9 ton per acre alfalfa crop. And this 470 lb of nitrogen per acre is in addition to what is needed to produce a crop or to produce meat.

Diagram indicates that every year, 31 tons (dry) biomass per acre per year is needed in order for 15% to go to soil organic matter (while 85% is lost), every year for 20 years to go from 1.7% to 11.1% soil organic matter. Also required every year is 470 lb N/ac, 47 lb P/ac, 19 lb S/ac. Figure 1 – Biomass and nutrients needed for 1.7-11.1% increase in SOM.

To top this all, Brown states (after mentioning his land with 11.1% SOM), “We’ve done this without the use of any synthetic fertilizers, pesticides, or fungicides.”

We are to believe that biodiversity-powered microbes free up large amounts of phosphorus, fix large amounts of nitrogen from the air, while plants produce 31 tons of biomass in a short North Dakota season, while also producing harvested crops and livestock?

I cannot say that this scenario is impossible, but I find it highly improbable, because if this is true, then it means that science has missed an astounding, extraordinary process. And it has been missed by not just agricultural soil scientists, but also those who work in prairies and forests, because, according to regenerative agriculture, this is how it works in nature. And we have been studying nature for a long time. And this is not just about a claim made by Gabe Brown; similar claims are commonplace in regenerative ag circles. If this and similar claims are true, then we are talking about a revolution in agriculture, which is what regenerative farmers and their supporters say it is.

ANOTHER PRINCIPLE However, there is another principle here: extraordinary claims require extraordinary evidence. What counts as evidence are peer-reviewed publications in scientific journals – I have looked for the evidence to support the claims of regenerative agriculture. What I have found are lots of YouTube videos, testimonials, articles and interviews. None of these sources are extraordinary evidence.

Extraordinary claims also require scrutiny, which is why I wrote this piece. I cannot disprove with words and calculations what Brown says he has observed in the field, but words and calculations can show that this is extraordinary, and so demand more evidence. I also wrote it to show the regenerative agriculture community the reasons why people like me, scientists and researchers, and those who believe in the scientific process, are skeptical of their claims.

If the claims of regenerative agriculture are real and repeatable, then they are of such magnitude (i.e. 1.7 to 11.1% SOM) that they should be easy to measure. So here is a challenge to regenerative agriculture. Provide the extraordinary evidence. If it exists, let me know and I will post it here. If the research still needs to be done, connect with researchers to start the process. Don’t let regenerative ag become the cold fusion of agriculture. Pursue rigorous science to demonstrate its value.

Another article about some of the extreme claims in regenerative agriculture http://www.agronomypro.com/be-careful-which-rainbows-you-chase.pdf